1. Field of the Invention
The present invention relates to blends of a sulfone polymer, such as polysulfone, polyether sulfone, or polyphenyl sulfone, and an impact resistant interpolymer. The resulting blends find utility as a raw material in the fabrication of formed parts.
2. Description of the Prior Art
Sulfone polymers are transparent high-temperature engineering thermoplastics. Three polymers of this type, which are commercially available, are polysulfone, polyether sulfone, and polyphenyl sulfone.
Blends of sulfone polymers and acrylonitrile-butadiene-styrene resins have been described in the prior art. For example, British Pat. No. 1,306,463 describes blends of a polysulfone resin and an ABS resin which have good flow properties, a very high heat distortion temperature, good impact resistance and flexural strength. U.S. Pat. No. 3,642,946 to T. S. Grabowski describes ternary blends of ABS graft polymer, polycarbonate and polysulfone having high impact strength and high heat distortion temperatures.
Blends of sulfone polymer and a three-stage acrylate/styrene-acrylonitrile composition are suggested by U.S. Pat. No. 3,655,826 to R. P. Fellmann et al. However, this patent at Col. 5, lines 65-70 also suggests that for certain types of polymers, if good impact strength is desired, the third stage should be derived from acrylate or methacrylate monomers, rather than from styrene and acrylonitrile, which is indicated as being responsible for good heat distortion temperature characteristics for the blend (Col. 5, lines 62-65).
Another three-stage interpolymer comprising acrylate, styrene, and acrylonitrile moieties is described in U.S. Pat. No. 3,944,631 to A. J. Yu et al. This interpolymer has been rather specifically described in the prior art as an impact improvement additive for polycarbonate resins (U.S. Pat. No. 4,148,842), for blends of chlorinated vinyl chloride and vinyl chloride polymers (U.S. Pat. No. 4,160,793), and for vinyl chloride polymers (U.S. Pat. No. 4,168,285). It has not previously been shown or suggested as an impact improvement additive for sulfone polymers.